Anderson, Brian D.O.Clements, David J.2026-01-022026-01-020022-247XORCID:/0000-0002-1493-4774/work/174739692https://hdl.handle.net/1885/733802776We define various ways in which linear-quadratic control problems can be robust and show that there are conditions which are simultaneously necessary and sufficient for robust problems to have a solution when such conditions do not exist for nonrobust problems.9en1978-03-0110.1016/0022-247X(78)90154-30017949512